Effects of tofacitinib on lymphocyte sub-populations, CMV and EBV viral load in patients with plaque psoriasis

BACKGROUND Plaque psoriasis is a debilitating skin condition that affects approximately 2% of the adult population and for which there is currently no cure. Tofacitinib is an oral Janus kinase inhibitor that is being investigated for psoriasis. METHODS The design of this study has been reported previously (NCT00678210). Patients with moderate to severe chronic plaque psoriasis received tofacitinib (2 mg, 5 mg, or 15 mg) or placebo, twice daily, for 12 weeks. Lymphocyte sub-populations, cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNA were measured at baseline and up to Week 12. RESULTS Tofacitinib was associated with modest, dose-dependent percentage increases from baseline in median B cell count at Week 4 (24-68%) and Week 12 (18-43%) and percentage reductions from baseline in median natural killer cell count at Week 4 (11-40%). The proportion of patients with detectable CMV and EBV DNA (defined as >0 copies/500 ng total DNA) increased post-baseline in tofacitinib-treated patients. However, multivariate analyses found no relationship between changes in CMV or EBV viral load and changes in lymphocyte sub-populations or tofacitinib treatment. CONCLUSIONS Twelve weeks of treatment with tofacitinib had no clinically significant effects on CMV or EBV viral load, suggesting that lymphocyte sub-populations critical to the response to chronic viral infections and viral reactivation were not significantly affected. Replication of these findings during long-term use of tofacitinib will allow confirmation of this observation.